Heat exchanger are large pieces of mechanical air and fluid handling equipment having large cross-sectional dimensions. Adjacent components of heat exchanger connect together at flanges with bolts. Gaskets seal the connection of the adjacent components to prevent leakage from the heat exchanger.
Periodically, or as necessary, the gaskets that seal the connections in heat exchanger are replaced. It has been the practice in the industry for the new gaskets to be custom manufactured, typically by a gasket distribution company local to the facility requiring the new gaskets. There are several reasons for this practice. Generally, no major company manufacturing small-diameter gaskets provides large-diameter gaskets for heat exchanger. Small diameter gaskets are generally available in a wide range of inner and outer diameters, generally having overall diameters of up to about twelve inches. For large-diameter applications, generally of twelve inches and greater, there are a number of different gasket patterns, and replacement typically is an infrequent occurrence. It is impractical to inventory replacement gaskets for large diameter applications.
In contrast, the smaller gaskets for fluid flow control devices are used more frequently, and manufacturers of gaskets maintain dies in a wide range of inner and outer diameters to manufacture small-diameter gaskets up to approximately twelve inches. Such smaller gaskets are easier to store in warehouses and ship to distributors or end-users for installation. The large-diameter gaskets however are more difficult to handle and store due to their size, the flexibility of the gasket, and the brittle nature of the sealing material of the gasket.
Presently, replacement large-diameter gaskets are generally made by gasket distributors which are local to the site requiring replacement gaskets. The replacement gaskets are made with a metal ring overlaid with sealing materials. The ring is cut using a gasket template laid over a large plate of sheet metal. The sealing material is typically cut from a sheet of calendared graphite having a layer of adhesive. Such product is available commercially in a number of thicknesses and densities. The sheet is laid on a table and the ring is placed on the adhesive layer. The gasket is then cut from the sheet. The ring is turned over and placed on a second sheet to coat the opposing side of the ring. The remaining materials are generally scrapped as waste, which comprises an additional cost. The gasket is then moved carefully to the heat exchanger and installed.
While these locally-manufactured gaskets have provided replacement gaskets for large-diameter sealing applications, there are drawbacks to their usage. These drawbacks include the inability to incorporate into the large diameter gaskets the improvements found in modern small diameter gaskets. The uniformity of the custom-made gasket varies one to another, and the overall quality depends upon the experience of the technician manufacturing the gasket.
Accordingly, there is a need in the art for an improved heat exchanger gasket, together with an apparatus and method of manufacturing improved heat exchanger gaskets. It is to such that the present invention is directed.